


double stuf

by armethaumaturgy



Category: Undertale (Video Game)
Genre: Begging, Cross (X-tale) - Freeform, Cunnilingus, Double Penetration, Dust (Dusttale) - Freeform, Ecto-Genitalia (Undertale), Explicit Sexual Content, Horror (Horrortale) - Freeform, Horror/Dust/Cross, Knotting, M/M, Multiple Orgasms, Size Difference, Vaginal Sex, cumflation
Language: English
Status: Completed
Published: 2021-02-08
Updated: 2021-02-08
Packaged: 2021-03-14 14:53:33
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,995
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29297682
Author URL: https://archiveofourown.org/users/armethaumaturgy/pseuds/armethaumaturgy
Summary: This wasn’t Cross’ first time dealing with him like this, far from it. He was always one of Dust’s first choices for help, but Cross was finding it hard todoanything to help with Dust actively fighting against him.The moment Cross moved a hand away from a thigh, Dust twitched so hard he almost kneed him in the face. His muttering reached a feverish pitch, words slurred together into an incomprehensible mess. No matter how many times Cross reassured him it was fine, Dust seemed to be focusing on everything but him.He had to concede he couldn’t do this on his own, not this time.
Relationships: Sans/Sans (Undertale)
Comments: 11
Kudos: 180





	double stuf

Cross’ phalanges dug into Dust’s thighs, but the skeleton was jerking under him, writhing and twitching. Cross had no idea if - or how much — he was hurting, but the half-delirious mumbling was making his SOUL clench as if Dust were physically squeezing it.

He could only catch bits and pieces of whatever he was mumbling about; it seemed he was parroting something, words not his own even as they tumbled off his tongue. He bucked again and almost knocked Cross off of himself.

This wasn’t Cross’ first time dealing with him like this, far from it. He was always one of Dust’s first choices for help, but Cross was finding it hard to  _ do  _ anything to help with Dust actively fighting against him. He could pin him down with a well-aimed bone attack or two, but he didn’t want to risk Dust jerking and hurting himself, nor feeling like he was in danger, because that would only end in a disaster.

The moment Cross moved a hand away from a thigh, Dust twitched so hard he almost kneed him in the face. His muttering reached a feverish pitch, words slurred together into an incomprehensible mess. No matter how many times Cross reassured him it was fine, Dust seemed to be focusing on  _ everything  _ but him.

He had to concede he couldn’t do this on his own, not this time.

His thumbs rubbed soft circles into the quivering magic of Dust’s legs, before tightening to stop the other from kicking him again. “I’m gonna teleport us,” he announced, giving Dust a moment to process the words and expect the little spark of magic as they touched the Void, and then they were in the kitchen. Cross held him steady as Dust all but fell against him, shaking and gripping onto his jacket.

Horror had turned their way at the distinct sound of a teleport, looking them up and down with a look that Cross could never place. His eye roved over Dust’s frame, the unchecked shaking and the desperate way he clung to the soldier as if to ground himself. From the look of things, it wasn’t really doing much.

Horror’s eye met Cross’.

“Can we bother you?” Cross asked, moving one hand to rub the back of Dust’s spine over the fabric of his hoodie. Dust shivered before melting into the contact, just a little. “I can’t hold him down alone.”

Horror said nothing for a moment. His browbones furrowed. “Not a bother,” he stated then, firmly. As he moved to turn the flame underneath the bubbling pot of stew, Cross felt a weight lift off his shoulders. It’d been silly to think Horror would refuse.

He corralled Dust closer to the bigger skeleton, holding him steady when he stumbled over his own shorts, barely hanging around one ankle.

Horror, to his credit, didn’t need any prompting.

The moment his hands pulled Dust against him, the smaller skeleton went still. Or, as still as someone like him could. Imagining him not twitching every so often, at least, didn’t seem correct. Dust ended up chest to chest with Horror and if Horror cared that Dust’s cock was pressing against the white of his shirt and staining it, he didn’t show it.

“Little lamb…” Horror muttered, tone soft as if he really  _ was  _ talking to a small animal. It almost sounded like he’d continue with the sentence, but then he didn’t, and instead leaned down a little to slide his hands beneath Dust’s ass.

Like it took him no effort at all, he picked Dust up and spun him around, but not before stealing a kiss that interrupted the quiet, ceaseless mumbling for a moment. He leaned against the edge of the counter and placed Dust onto the jut of his own hip bones, holding him up by nothing but his spread thighs.

It left both his dripping entrance and bobbing cock on display for Cross, and the angle Horror was leaning at ensured that no matter how hard Dust jolted, he wouldn’t fall.

Looking at them like this, Cross was struck by the sheer difference between them. Chock full of LV — they’d both been at twenty for a long, long time by now — that manifested completely differently. 

Dust was the smallest one out of them, maybe save for Nightmare, and though he was only an inch or so shorter than Cross, next to Horror, he looked  _ tiny _ . There was a good head of difference between them, and Horror’s hands were able to fully encircle Dust’s thighs.

"Prime for a slaughter, ain'tcha," Horror said, nuzzling the side of Dust's skull where it rested in the crook of his neck. It was as much a nudge for Cross as it was soothing for Dust.

Cross stepped up to them, effectively squishing Dust between himself and Horror. A hand traced over Dust’s stomach, down the tensing ecto to his cock, and Cross wrapped his phalanges around it. Horror had started to match Dust’s delirious muttering with his own, slower kind.

“You’re so pretty, lambchop,” Cross could hear, “Gonna take care of you.” 

Dust’s cock was leaking precum nonstop, making Cross’ job that much easier. His cunt was the same; electricity sparkled through Cross’ finger as he dragged it through the dripping slick. Slowly but surely, Dust was making a puddle on the kitchen tiles.

Cross dropped down to his knees. This way, there’d be less cleanup, he reasoned to himself as he held Dust’s hips, phalanges brushing Horror’s. The entrance was spasming just as much as the rest of his body. One time, Dust had apologized for his body, the twitching and all; Cross still wasn’t sure if it’d been in another fit of delirium or not, but he hadn’t been the only one to reassure him it was alright. And, truth be told, it always felt amazing to have the velvety walls squeeze down out of nowhere. Just the thought of it made the tightness in Cross’ shorts more prominent, even if he was still able to ignore it.

Dust jolted at the first swipe of his tongue across the wet folds, but Horror held him steady.

“That’s it,” the bigger skeleton cooed, thumbs rubbing over the false flesh of his thighs. “Focus on… us.”

Cross looked up just in time to catch Dust peering down at him. His mismatched eyelights were hazy along the edges and unfocused, but at the very least, they weren’t darting all around anymore. Cross held the eye contact as he lapped at the entrance, one hand reaching up to wrap around Dust’s cock again.

Dust was still mouthing something, but the mutters had turned into wet panting and choked moans. He was getting closer and closer to returning to himself. And to an orgasm, if the way his ankles locked behind Cross’ skull was anything to go by. Cross swiped his thumb over the head of his cock, just the way he knew Dust liked, at the same time he wriggled his tongue into his entrance.

The effect was immediate; Dust cried out wordlessly, arching his back as far as the position allowed him to. Slick dripped down Cross’ chin as more of it painted striped across Dust’s shirt, all of it tingling with the charged static of magic. 

His twitching died down to a shivering, his whole body sagging against Horror’s chest as he gasped to regain his breath.

“Lamb…? You with us?” Horror asked, craning his head to kiss him. His answer was a muffled hum. The next time Dust looked down at Cross, he was actually looking at him.

“Fuck,” was the first coherent word out of him, outside a mad chant on how best to gain more LV.

Cross couldn’t help his lopsided grin, petting one of his thighs. “That’s the plan. You want in, big guy?” Cross asked, looking at Horror who, in turn, was watching Dust with an all-too-obvious fondness.

He shook his head. “Maybe later, when it’s… if it’s necessary,” he said. Dust, however, was not pleased with his answer.

“No,” he gasped, flexing his fingers where they were bunched in Horror’s sleeves. He turned to kiss him again. “I want you.”

If that wasn’t  _ the  _ hottest thing Cross had ever seen, it was damn close.

Dust looked back down at him next and started unhooking his legs from his shoulders. He was breathless as he spread them, his hood halfway from sliding down the back of his skull. “Both of you.”

Scratch whatever he’d just thought, because  _ that  _ was the hottest thing he’d ever seen.

“You sure, lambchop?” Horror asked, “Cross… can fill you up.”

Lucidity had most definitely returned to Dust, though the same couldn’t be said about shame. “I want both of you,” he said defiantly, wiggling in his perch on purpose, to make Horror hiss as the ecto-flesh rubbed against his sensitive bones through the shorts separating them. “I want you both  _ in  _ me. Now.”

The magic still sparked across Dust like a live wire, so Cross caught his hand as it tried to reach around to Horror’s pelvis. He stood up and kept a hold of it, squeezing back when Dust’s fingers twitched.

“Let me,” he said, repeating Dust’s previous movement with his other hand. It slipped into Horror’s shorts and rubbed over his pubic symphysis; the bone was enticingly hot to the touch.

Horror didn’t need much, just a little spark to help his broken magic.

With a little pull, the magic crackling in Cross’ hand mixed with Horror’s and shaped itself into a thick cock. Cross pulled his shorts down before pulling away completely, so it could spring free. Horror’s already labored breathing hitched further as it rubbed over the slick folds of Dust’s pussy. Horror was proportional  _ everywhere _ , and Cross was having doubts whether they’d both even fit, much less with their knots.

“Ready?” Horror asked, adjusting his grip on Dust’s thighs. His answer was a vehement nod, followed by a high whine as his cock kept teasing along the slit, barely providing any stimulation.

Cross watched, enraptured at his own color adorning Horror. His knot kept that rusted red of his, but the rest of the shaft was Cross’ purple, just a few shades off from Dust’s vibrant lilac.

Dust let out a long, drawn-out moan when Horror started pushing in. His mouth hung open, tongue conjured and lolling out just enough that spittle ran down his chin. He’d started muttering again, but this time it was a string of profanities punctuated with pleas and compliments. It made Cross’ mouth feel dry.

“C-Calm down, lambchop,” Horror grunted, holding the smaller skeleton still, despite the very vocal demands to start moving. “Gotta… acclimate.”

“I’m fine!” Dust cried, trying his damndest to buck down and take more, growling deep in his throat when he couldn’t. He was impaled on Horror’s dick down to the knot, ecto distended from the size even if it was almost invisible through his stomach. Cross ran his phalanges down the bump and he could see the way Horror shivered at the sensation.

“You really wanna try taking both?” Cross asked, just to make sure. Dust arched up into his touch, only making Cross press further into the fake flesh.

“Fuck, yes—! Criss-cross! I can fucking take it!”

Cross’ cheeks heated up at the shameless begging and he could only nod. His hand drifted down, to where Horror’s girth was spreading him open. Horror muffled his groan at the touch to his knot in Dust’s neck, mouthing at the vertebrae and barely skirting his teeth over the sensitive bones. Dust canted his head to the side to give him more space, so Horror took full advantage of the invitation and sunk his teeth into the bone, leaving behind a crescent-shaped mark in his wake.

Cross’ fingers teased along Dust’s lips, gathering up the leaking slick before he pressed in purposefully, slipping a phalange inside alongside Horror. Dust whined, and both Cross and Horror groaned in sync when he clamped down.

“You’re so tight,” Cross marveled, like he didn’t say the exact same thing every single time. With just a bit of coaxing, the ecto-flesh adjusted and Cross was able to slip two fingers inside.

Dust clawed at the hands holding him, biting back another moan. “Fucking, fuck, fuck…! Please! Please fucking move!” he begged, legs twitching at the feeling of Cross scissoring his fingers.

Horror nodded down at Cross, watching his hand move with a hawk-like intensity even as he kept leaving marks along the column of Dust’s neck, his hood nosed off to the side. He started moving, barely lifting the smaller skeleton before letting gravity sink him back down. It wasn’t enough, but Dust cried out anyways, stuck between trying to match Horror’s pace and Cross’ fingers.

Another stream of curses and magic sparking dangerously sling Dust’s joints, and Cross deemed him as ready as he’d ever be. Pulling his fingers out earned him a disappointed whine that turned into a groan when Dust opened his sockets and saw him shimmying out of his shorts.

Cross sighed out in relief once his cock was freed, and pointedly ignored the wet stain he’d left on his shorts. Dust’s legs spread minutely, as if inviting him in.

Horror stopped moving and let him get situated between Dust’s legs again, his cock teasing along the stretched entrance.

“Come on!” Dust hissed, impatient, and Cross gave him what he’d been begging for, his own patience wearing thin.

Dust’s mouth fell open in a soundless scream as Cross pushed in, body seizing up and hands frantically scratching at Cross’ back. He went lax between them, walls fluttering out of tune with his hitching breath. 

Horror chuckled, deep and gravelly. “Felt that good, huh?”

Cross was stunned, the simple knowledge that Dust had come again from him just pushing in, coupled with the tight heat of his cunt and the pulsing of Horror’s cock next to his, bringing him close to his own edge.

“Fucking  _ move _ !” Dust shouted, so Horror tightened his grip and pulled him up, resuming his previous pace. Each thrust rubbed along the side of Cross’ cock, pleasure crawling up his spine like bursts of molten fire.

Gritting his teeth, he tried to match Horror, hips stuttering on the first few thrusts. Dust clung to him like a lifeline and if he wasn’t still wearing his hoodie, there would’ve definitely been scratch marks left all over his shoulder blades. Cross found himself thinking it was a shame he hadn’t taken it off.

They found a rhythm that had Dust crying out, Cross pushing in when Horror pulled out, and while he wasn’t as long, Cross was at the perfect angle, if Dust’s desperate sounds were anything to go by.

Horror finally pulled away from Dust’s neck, the vertebrae a veritable mess of bites and marrow, and leaned over his shoulder to kiss Cross. “Close…” he grunted, and he sounded as wrecked as Dust looked.

“Give me- Gimme all of it,” Dust slurred in return, arching off into their thrusts and dragging his cock across Cross’ shirt. It’d be as ruined as his shorts by the end of this, but Cross didn’t mind.

“Want me… to knot you?”

Dust craned his head to the side again, to capture Horror’s teeth in a desperate kiss, nodding so hard he almost headbutted him. “Fuck, please! Knot me! Both of— both of you!”

He’d obviously not calmed down from his previous orgasm, and it showed in how much he shivered, magic flaring up each time Horror hit the back of his magic just right. Cross wasn’t far behind, he could feel his knot start to inflate, so he held Dust still by the hips — or as still as he could.

For a long second, Cross thought they wouldn’t fit, but Dust’s ecto gave way with a wet noise and Cross’ knot popped inside, followed by Horror’s on the very next thrust.

It was tight and so, so hot, and Dust cried for them with a scream that echoed through the kitchen. Cross could feel his release splattered against his hoodie and he managed a couple more shallow, frantic thrusts before he was coming too, leaning up to kiss Dust, if only to muffle his own moan.

Horror bit down on one of the marks he’d left on Dust’s neck as he came. The smaller skeleton was stretched so wide around their knots, unable to move a muscle as they filled him up, stomach distending further as they held the cum from escaping.

Dust was a mess; clothes all askew and face stained with tears and spit, and he looked like he was seconds from passing out. Cross placated him with softer kisses as they waited for their knots to go down, Dust’s death grip softening into an embrace, tangled all around Cross’ neck.

The static magic crackling along his bones had subsided, no longer as charged, and he looked calmer, languidly twining his tongue with Cross’.

“Better?” Horror asked, licking over the bleeding bites as if to soothe them. It made Dust shiver, a content sound coming from the depths of his throat. It was so close to a purr that Cross could find it naught but endearing.

“Will feel better when I’m not chock full of cum,” Dust muttered, though he made no attempt to move away. Cross grinned.

His hand snaked between them and rubbed over the swell of Dust’s stomach. His purple and Horror’s red mixed in the ecto-flesh, but the red was the only one that was really visible. He pressed down and Dust keened, folding into himself as much as he could.

Cum gushed around their knots, no longer wide enough to hold it in.

Horror laughed at the shivering mess Dust had been reduced to again, and Cross pressed down again. Having to mop the floor was worth it to see Dust’s eyelights guttering out along with the breathless noises.

“Sure you will.”

**Author's Note:**

> thanks to @avosettas for the title. heh.
> 
> twitter is @esqers, come hang out♥


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